This invention generally relates to a processing apparatus for sheet metal components produced in short production runs.
The production of sheet metal components having complicated shapes in short production runs, such as for the production of relatively large components such as wing components of airplanes or plating of ships, often are performed using a so-called stretch-forming apparatus. This apparatus is designed to pull a plate (sheet metal) across a convex form (tool), so that the metal component is shaped in the desired three-dimensional shape.
Other laser processing units are known, which are used, for example, to cut sheet metal or to weld various components.
In addition, the combination of a mechanical sheet metal processing apparatus with a laser processing unit is known. For example, DE 4425033 C2 discloses an apparatus for pressure shaping sheet metal pieces. The apparatus consists of a die and a pressure roller, which presses the rotating sheet metal onto the die. To facilitate this pressure processing, a laser head is designed to direct a laser onto an area just ahead of the pressure roller. If the sheet metal piece rotates, the laser thus heats the entire circular area of the metal piece to be shaped with the pressure roller. In this manner, the processing step is intended to be performedat a higher processing temperature.
Likewise, in order to facilitate the bending process and to localize the same, a laser source is used as a source of heat in the process and apparatus described in DE 4228528 A1. The apparatus described therein has a platform, which can be moved in two directions, which are respectively equipped with an x and an y direction motor. The platform includes a clamping mechanism for holding the sheet metal. With this arrangement, the sheet metal is clamped in a first location at the edge. The apparatus further includes a multi-jointed arm above the platform that has a clamping unit at its free end. This clamping unit serves to clamp the sheet metal at a location directly opposite the first spot. The multi-jointed arm contains various driving units, so that it can be moved in three dimensions in a controllable manner.
The apparatus also includes a designated spot above the table for a laser head, which is movable in three dimensions and which generates a laser beam movable along a specified path over the sheet metal. This serves to heat linear sections of the sheet metal, so that the bend of the sheet metal concentrates along this area, whenever the clamp held on the arm is moved. In this fashion, sheet metal can be bent in three dimensions without the use of mechanical forms.
The bending apparatus according to DE 4228528 A1 is a special apparatus, which does indeed produce various shaped components without a mechanical die. However, the potential processing steps are limited to bending steps. This limits the applicability of this processing unit.
Accordingly, in view of the foregoing, a general object of the present invention is to provide a processing apparatus for shaping sheet metal which is capable of numerous processing operations.
According to one embodiment, the processing apparatus of the present invention includes at least two clamping mechanisms, which are arranged such that they can clamp the sheet metal at two separate locations. A motor serves to adjust the distance between the clamps in such a way and, if necessary, with such force as to facilitate a stretching of the cold or partially pre-warmed sheet metal. In this way, the sheet metal may be drawn across a die held in a receptacle in order to be simply and quickly formed in the desired shape. In addition, a beam processing apparatus, such as a laser processing unit, is designed to operate on the sheet metal before, during or after the stretching-forming step. A cutting operation is an example of such an operation that can be performed by the beam processing unit. Thus, it is possible, for example, to cut the sheet metal immediately after stretching. For example, the pressure roller may be removed and/or the outer edge may be finished. The integration of this process into the stretch-forming apparatus facilitates economic and flexible processing, even for very short production runs. The gripping jaws (clamps) of the stretch-forming apparatus thus also serve as the tensioning apparatus for the cutting operation performed by the beam processing unit. In addition, the beam processing apparatus can serve to weld reinforcements, such as stringers or ribs, onto the concave or convex side of the sheet metal (i.e. outside or inside). In such a case, the stretch-forming die can be used as a tensioning mechanism, if the reinforcements are welded onto the outside. If the reinforcements are welded onto the inside, they may be seated into notches of the stretch-forming die, where the welding can then be executed as a covered laser weld from the outside. Otherwise, stringer and rib frames may be used as directly forming components that are clamped into an apparatus. The sheet metal is tensioned across these components, where the gap between the elements to be welded is simultaneously reduced.
In addition, it is possible to pre-bend the reinforcements to be welded in the stretch-forming die or in its vicinity and then to weld from the side of the reinforcement. Thus, the beam processing unit may be located either on the convex side of the stretch-forming form, i.e. above the sheet metal, or below it.
The integration of the beam processing unit into the stretch-forming apparatus not only enables the completion of sequential processing steps using one and the same apparatus, thus saving handling and positioning time as well as investment costs for another clamping apparatus, but also allows for the design and execution of processing operations that would be impossible with independent units. For example, a piece of sheet metal may be first stretched and then treated with a laser, such as to apply openings, cut a component and/or weld on additional components. Subsequently, the bending or stretching may continue. Thus, new elements with totally different properties may be produced. It is also possible to target the heating during the stretch-forming process to specific areas of the sheet metal to aid in the shaping process. In this way, it is possible to produce sheet metal components with a higher or reduced thickness in targeted areas.
The beam unit includes a beam head, which focuses the beam onto the work piece. The beam head is at least movable in a targeted manner by way of a positioning mechanism. In the simplest case, the positioning unit is a movable bridge that spans the stretch-forming apparatus. With such an arrangement, the beam head can be focused onto any spot on the work piece. The bridge construction does not obstruct access to the workspace of the stretch-forming apparatus, which, if desired, may be operated also in the conventional way, i.e. without the additional beam processing.
In addition to the beam processing unit, an additional source of heat designed to affect the work area may be included. For example, this additional source of heat may be designed to heat larger areas of the work piece. This could serve to improve the welds to prevent hot breaks or to soften certain parts of the work piece. The source of heat may consist of an induction coil or of several induction coils, which move with the beam head or which have a separate motor. The distribution of heat energy and the temperature at the treatment location may be influenced by a corresponding control unit, if provided. The residual heat from the heat source may also be used by the beam processing unit. The heat source may also serve to pre-heat the work piece prior to welding or molding.
Preferably, the apparatus includes a unified control unit, which controls the actions not only of the stretch-forming apparatus as well as the beam processing unit and, if present, the induction heating unit. The form of the metal piece being worked on is determined by the stretch-forming die (the tool). Its form and quality are also determined by the control program, which controls the stretch speed, pre-warming, cutting processes and welding processes.
In an advantageous embodiment of the invention, the beam processing unit comprises a laser beam processing unit. If needed, this could also be used for cutting. For this purpose, the relevant laser head is preferably also equipped with a cutting gas supply nozzle, which receives cutting gas in a measured manner.
In an alternative design, the laser head serves as the welding head. As an alternative, the laser head may be switchable to various operational modes, so it can handle a welding operation just as well as a cutting operation, or the apparatus has a switchable receptacle for receiving several different heads.
The unified control unit for all components of the processing apparatus enables coordination of the beam processing and the mechanical stretch-forming process, so that the operations need not be run sequentially, but may even be run simultaneously by combining a laser operation with a stretching operation. During a stretching operation, various areas of the sheet metal piece may be heated, cut or welded to shape the metal components in a particular fashion.
These and other features and advantages of the invention will be more readily apparent upon reading the following description of an exemplary embodiment of the invention and upon reference to the accompanying drawings wherein: